# 101

## What Is Roof Pitch?

The pitch of a roof is how steep the roof is. It's calculated by dividing the height of the roof by the width of the roof. This is often expressed as a ratio, with the height (or "rise") listed first and the width (or "run") listed second. In the United States, this ratio is usually given as the number of inches the roof rises for every 12 inches of horizontal distance (or "run"). For example, a roof with a 4:12 pitch rises 4 inches for every 12 inches of horizontal distance.

• 4:12 pitch (18.43° angle, 16.05% grade slope)
• 5:12 pitch (22.62° angle, 21.15% grade slope)
• 6:12 pitch (26.57° angle, 26.57% grade slope)
• 7:12 pitch (30.26° angle, 32.33% grade slope)
• 8:12 pitch (33.69° angle, 38.41% grade slope)
• 9:12 pitch (36.87° angle, 44.81% grade slope)
• 10:12 pitch (39.81° angle, 51.52% grade slope)
• 11:12 pitch (42.51° angle, 58.54% grade slope)
• 12:12 pitch (45° angle, 66.67% grade slope)
• 13:12 pitch (47.26° angle, 75.01% grade slope)
• 14:12 pitch (49.4° angle, 83.56% grade slope)
• 15:12 pitch (51.34° angle, 92.31% grade slope)
• 16:12 pitch (53.13° angle, 101.27% grade slope)
Most common roof pitch sizes